Air pollution is a direct hazard to the environment and to our health. According to the World Health Organisation, polluted air is air whose chemical composition may adversely affect the health of humans, animals and plants, as well as water and soil, which is usually contaminated by sulphur dioxide, nitrogen oxides and particulate matter.
The word "smog" derives from two English words: "smoke" and "fog". Smog is an artificial atmospheric phenomenon, dangerous for our health. It occurs when two factors – specific atmospheric conditions – are present simultaneously: fog in windless weather and air pollution associated directly with human activity.
Allergies are a reaction of the immune system to certain factors. Allergies can be caused by substances present in our immediate environment, the most common allergens being pollen, animal fur, dust and mould. The number of people suffering from various allergies increases year after year, primarily affecting city dwellers.